The invention relates to a fan module, and more specifically to a control device providing fan speed modulation according to the number of loads, and a fan module with the control device.
With improvements in technology, the number of electronic components inside electronic devices has increased, and the generated heat during operation is also increased corresponding to the number of electronic components. To maintain performance, fans are conventionally used to dissipate heat therefrom. However, because the size of the housings of the electronic devices and the number of components therein are different, and heat generated in middle-sized and big-sized electronic devices is high, at least two fans are often used so as to achieve the effect of heat dissipation. Conventionally, a fan module comprises an integrated plurality of fans in a frame and is controlled by a control device.
Electronic devices with differing load numbers require fan modules having different powers. Conventional fan modules utilize fully powered and power-saving operating modes. Electronic devices with fewer loads require only the former mode while those with more loads require both modes. As shown in FIG. 1, an electronic device 1 includes a fully powered fan module 2, a power-saving fan module 3, and a plurality of hot-plug loads 4. With fewer loads 4, the power-saving fan module 3 can dissipate heat. With increased loads 4, the fully powered fan module 2 will start for heat dissipation.
Further, with temperature detection components built into fan modules 2 and 3, control devices therein generate a control signal corresponding detected temperature variations and transmit the control signal to a plurality of fans. FIGS. 2A and 2B show relationships between temperature and speed with respect to the fan modules 2 and 3. As shown in FIG. 2A, the relationship between the speed and temperature is linear, that is, with increased temperature (t1 to t2), the speed of the fans is increased accordingly (r1 to r2). However, in practice, the relationship between the temperature and speed may not be as direct. With the impact of noise, the line may become a curve, thereby degrading the performance of the control devices. Moreover, as shown in FIG. 2B, when the temperature exceeds the threshold temperature t3, the speed of the fans is increased to speed r2 from speed r1. However, such rapid speed changes can reduce the life of electronic devices with more loads.
With concentration of components inside electronic devices and reduced size thereof, the amount of heat generated thereof increases. Thus, it is necessary to obtain a fan module with better heat dissipation performance and a control method thereof is called for.